Cyclic graphs

So far, all graphs have been acyclic, but we can generalize these results to show that the appropriate categories of cyclic graphs give the intial category with a partial trace, that is a category with a feedback operator: The notion of partial trace is a generalization of Joyal, Street and Verity's traced monoidal categories, and adapts Hasegawa's semantics for call-by-name languages to call-by-value.